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RE: [Opal] beamline simulation for low energy radioactive ion beams

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  • From: Van de Walle Jarno < AT>
  • To: "Adelmann Andreas (PSI)" <andreas.adelmann AT>
  • Cc: "opal AT" <opal AT>
  • Subject: RE: [Opal] beamline simulation for low energy radioactive ion beams
  • Date: Wed, 6 Apr 2022 11:34:33 +0000
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Hello Andreas,


Thanks for your quick reply!


There seems indeed some misinterpretation of restmass and kinetic or total energy …


The restmass for an ion of mass 100 (say, for ease we consider Sn-100) is than 100*amu = 93149.41 MeV

The kinetic energy is only 0.06 MeV

Total energy follows naturally.

Gamma = 1.0000006441

B.rho = 0.352663 T.m

These values are correct in the input file.


So in the ‘BEAM’ statement I :

- omit the PARICLE definition (since it’s none of the predefined symbolic constants). When running OPAL notifies it’s assigning ‘UNNAMED’

- MASS = rest mass, correct ? Not total mass ?

- CHARGE = 1+

- BEAM ENERGY I specify as GAMMA (since it has highest priority, as read from paragraph 14.1 in the manual)

- BFREQ I assigned according to your suggestion (although we have a continuous beam here, but I suppose this doesn’t really affect the tracking ?)

- BCURRENT = 1e-6


When running like this, I get:

=> Momentum is zero ?


And weird Ekin and dEkin definitions in “BUNCH” output


Can the code really be used for none predefined particles, like I try to do here ?


Many thanks in advance for any further assistance!

With kind regards







From: Adelmann Andreas (PSI) <andreas.adelmann AT>
Sent: woensdag 6 april 2022 12:45
To: Van de Walle Jarno < AT>
Cc: opal AT
Subject: Re: [Opal] beamline simulation for low energy radioactive ion beams


Hi Jarno you need to define the charge for example 



REAL f1   = 50.65;  // MHz 



"RIB": BEAM, MASS=E0*1e-3, charge=1.0, ENERGY=E_TOT*1e-3, npart=10.0, BCURRENT=1.0E-6, BFREQ= f1;


Still, something seams to be off with the rest-mass. Consider to check by printing some values like:


value, {sr_gamma, E0};



Otherwise I will look at this again.




Cheers Andy 

Dr. sc. math. Andreas (Andy) Adelmann
Head a.i. Labor for Scientific Computing and Modelling 
Paul Scherrer Institut OHSA/ CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Zoom ID: 470-582-4086 Password: AdA

Zoom Link:

Friday: ETH HPK G 28   +41 44 633 3076
The more exotic, the more abstract the knowledge, 
the more profound will be its consequences.
Leon Lederman 

On 5 Apr 2022, at 15:52, Van de Walle Jarno < AT> wrote:




I’m new to OPAL and I’m trying to simulate a beamline for radioactive ions, which I did in MAD-X, now in OPAL.

The properties of the beam are:

Mass = 100 (amu)

Energy = 60 keV (!)

The beamline consists of 4 quad doublets and 1 dipole (112 degrees).

In MAD-X this runs smoothly and I wanted to check first of all if I can get similar results with OPAL. The next step would be to include a real 3D magnetic field map for the dipole in OPAL (which is not possible in MAD-X).


The first results are not encouraging L

I encounter multiple issues – which are probably related to a misinterpretation of the input file needs …


- when including the dipole, the tracking takes way too long to be realistic (so somewhere the tracking blocks)

- If I exclude the dipole (like in the attached inputfile), I see that The Kinetic energy of the beam is suddenly 4.528 GeV with dE = 19.686 MeV ?! No idea why …


I’m in any case convinced that OPAL could help us further in the simulation of our Radioactive Ion Beam beamlines and in the future our 100 MeV proton accelerator.

May I ask you to run the attached input file and/or hint towards my (obvious, maybe J) mistakes ?


Any help is highly appreciated !

Many thanks in advance and kind regards





Jarno Van de Walle, PhD
Beam physicist

+32 14 33 84 16 ǀ +32 470 20 98 31




Belgian Nuclear Research Centre

Boeretang 200 - 2400 Mol – Belgium






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